Sweet hat, the only thing i would suggest is to color correct the team colored portions to the medic's color scheme. Maybe have them the same color as his gloves? For that the red already seems close, but the blue is noticeably darker.

Pros: Well done model and smooth textures. Not too complicated, fits TF2. Looks overall, just very nice.
Cons: Restricted to the medic.
Improvements: Different sizes for every class? Unlikely, I know.
Notes: 9.8/10

Pros: Excellent model, the textures perfectly fit the TF2-niverse and overall it looks true to the original. The enviro map is a nice touch as well.
Cons: Er...none?
Improvements: Maybe...make the red "button" along the side glow and/or flash periodically? Possibly fill in the recessed panels with a little bit of black? Course I'm just splitting hairs here.
Notes: Instant download, good job.